<div id="login-container" class="row">
    <h1>User Login</h1>
    <br><br>
    <form [formGroup]="userForm" (ngSubmit)="onSubmit()"> 
        <label for ="user_username">Username:&nbsp;</label>
        <input id ="user_username" type="text" formControlName="user_username" placeholder="please input username"
                required autocomplete="user_username">
        <br><br>
        <label for ="user_password">Password:&nbsp;</label>
        <input id ="user_password" type="password" formControlName="user_password" placeholder="please input password"
                required autocomplete="user_password">
        <br><br><br>
        <button id="login-submit-btn"type="submit" [disabled]="!userForm.valid">Submit</button>
        <br><br>
    </form>
</div>